The contribution of PALB2 c.2323C>T [p. Q775X] to the causation of breast cancer in French-Canadians appears to be lesser than that attributable to the most common founder alleles in BRCA1 and BRCA2, but the young age at diagnoses and associated familial history of breast cancer suggest that this variant should be added to the panel of deleterious mutations screened for assessing breast cancer risk in this unique population. This evidence concerns the gene BRCA1 and breast cancer.